Softibe, who designed the CE, IIRC, suggest putting it last. That's good enough for me.
There was a massive debate about this when it came out, I will try to find the thread, if I have time. Craig did some very interesting tests on the different emulations.
One train of thought was that the effects would be exaggerated if put before compressors, etc.
As to trying to emulate the "real world":
In the good/bad old days, we would often record direct to tape to get as clean a signal as possible, and then bring it into the console for mixing. The inserts (compressors, etc.), would come first in the chain and then pass through the rest of the desk. So maybe putting it last would be more realistic.
Obviously, this wasn't the only way to work, so I guess there is no hard and fast rule - just like the analog days.
Finally, Seth P, Brandon, Noel, Softube etc seemed to recommend using it last, so make of that what you will.